Adding a C wire for Nest E


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Old 04-07-20, 08:27 PM
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Adding a C wire for Nest E

I've been having a trouble (low battery) with a new Nest E thermostat with a series 2 burnham boiler, I determined it probably needs a C wire added to work properly. I pulled a new wire and tried hooking it up to the C terminal but the nest wasn't detecting any power. I've attached the wiring diagram and a picture of the transformer.

Thanks
 
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Old 04-07-20, 09:35 PM
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Welcome to the forums.

You have three wires connecting the nest. They must be in the correct location.
Connect the white wire to G on the fan center and to W1 on the nest.
Connect the red wire to R on the fan center and to Rh on the nest.
Connect the green wire to C on the fan center and to C on the nest.
 
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Old 04-08-20, 05:26 AM
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The green wire is now disconnected. I removed it when the Nest gave me an error basically saying no power at c terminal while it was hooked up. the red and whites are as shown. Are you saying that based on the wiring diagram the C terminal on the transformer should be the right one for the common wire? Because that is not working.
 
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Old 04-08-20, 08:36 AM
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Hi, do you have a volt meter? test between R&C at the Stat, should be 24VAC.

Geo
 
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Old 04-08-20, 09:28 AM
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I can't positively see how the red and white wires are connected but if the red wire is on Rh at the thermostat..... it must be on the R transformer terminal.
 
 

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